Table 6 Comparison of calculated (B3LYP/6-311ϩG(2d, 2p)//AM1)
and experimental electron affinities for some C6H5X and C6F5X
compounds
14 J. N. Kirwan and B. P. Roberts, J. Chem. Soc., Perkin Trans. 2, 1989,
539.
15 B. P. Roberts and A. J. Steel, J. Chem. Soc., Perkin Trans. 2, 1994,
2411.
Substrate
Calcd. EA/eV
Expt. EA/eVa
16 V. P. J. Marti and B. P. Roberts, J. Chem. Soc., Perkin Trans. 2, 1986,
1613.
17 D. P. Curran, Synthesis, 1988, 417.
18 D. V. Avila, J. Lusztyk and K. U. Ingold, J. Am. Chem. Soc., 1992,
114, 6576.
19 D. V. Avila, C. E. Brown, K. U. Ingold and J. Lusztyk, J. Am. Chem.
Soc., 1993, 115, 466.
20 D. W. Snelgrove, J. Lusztyk, J. T. Banks, P. Mulder and K. U. Ingold,
J. Am. Chem. Soc., 2001, 123, 469.
21 D. V. Avila, K. U. Ingold, J. Lusztyk, W. H. Green and D. R.
Procopio, J. Am. Chem. Soc., 1995, 117, 2929.
22 L. Valgimigli, J. T. Banks, K. U. Ingold and J. Lusztyk, J. Am. Chem.
Soc., 1995, 117, 9966.
23 M. H. Abraham, P. L. Grellier, D. V. Prior, J. J. Morris and
P. J. Taylor, J. Chem. Soc., Perkin Trans. 2, 1990, 521.
24 P. A. MacFaul, K. U. Ingold and J. Lusztyk, J. Org. Chem., 1996, 61,
1316.
ؒ
ؒ
C6H5O
2.20
3.19
1.01
2.59
0.25
1.05
0.35
0.96
2.25
3.34
1.01
2.7
C6F5O
ؒ
ؒ
C6H5
C6F5
C6H5CN
C6F5CN
C6H5COCH3
C6F5COCH3
C6H5CH᎐CH2
0.26
1.08
0.33
0.88
Ϫ0.20
0.51
Ϫ0.25b
᎐
᎐
c
C6F5CH᎐CH2
a From ref. 45 unless otherwise noted. b Ref. 46. c Not available.
an alkyl chloride. The concentration of the hyponitrite was 0.5
mM, i.e., ca. 4% that of the Et3N→BH3; the concentration of
which was 12 mM. Thus, since almost two tert-butoxyl radicals
are generated from each molecule of hyponitrite, only ca. 8% of
the amine–borane was consumed. The concentration of n-PrBr
was 10 mM and the concentrations of the alkyl chlorides were
adjusted so that the yields of Et3N→BH2Br and Et3N→BH2Cl
were very roughly equal ([RCl] varied from 0.5 to 5 M). The
relative yields of these two products were measured by 11B
NMR: BCl (Ϫ5.5 ppm) and BBr (Ϫ8.0 ppm) both relative to
(added) Et2OؒBF3.
25 M. Lucarini, G. F. Pedulli and L. Valgimigli, J. Org. Chem., 1996, 61,
1161.
26 C. Tronche, F. N. Martinez, J. H. Horner, M. Newcomb, M. Senn
and B. Giese, Tetrahedron Lett., 1996, 37, 5845.
27 J. A. Baban, J. P. Goddard and B. P. Roberts, J. Chem. Res. (S),
1986, 30.
28 Gaussian 98, Revision A.7, M. J. Frisch, G. W. Trucks, H. B.
Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, V. G.
Zakrzewski, J. A. Montgomery, Jr., R. E. Stratmann, J. C. Burant,
S. Dapprich, J. M. Millam, A. D. Daniels, K. N. Kudin, M. C.
Strain, O. Farkas, J. Tomasi, V. Barone, M. Cossi, R. Cammi,
B. Mennucci, C. Pomelli, C. Adamo, S. Clifford, J. Ochterski,
G. A. Petersson, P. Y. Ayala, Q. Lui, K. Morokuma, D. K. Malick,
A. D. Rabuck, K. Raghavachari, J. B. Foresman, J. Cioslowski,
J. V. Ortiz, A. G. Baboul, B. B. Stefanov, G. Liu, A. Liashenko,
P. Piskorz, I. Komaromi, R. Gomperts, R. L. Martin, D. J. Fox,
T. Keith, M. A. Al-Laham, C. Y. Peng, A. Nanayakkara,
C. Gonzalez, M. Challacombe, P. M. W. Gill, B. Johnson, W. Chen,
M. W. Wong, J. L. Andres, M. Head-Gordon, E. S. Replogle and
J. A. Pople, Gaussian Inc., Pittsburgh PA, 1998.
Theoretical calculations
The geometry was first optimized using the AM142 semi-
empirical method for both the dipole moment and the electron
affinity calculations. The AM1 geometries were then used to
calculate the dipole moment and the single point energies were
computed using the B3LYP functional43,44 with the 6-311ϩ
G(2d, 2p) basis set.
The electronic energies and zero-point energies were summed
to give E0, the total energy at 0 K. The electron affinities were
calculated as E0 (anion) Ϫ E0 (parent). The validity of the
29 C. Reichardt, Solvents and Solvent Effects in Organic Chemistry,
VCH Verlagsgesellschaft, Berlin, 1990.
30 L. Valgimigli, K. U. Ingold and J. Lusztyk, J. Org. Chem., 1996, 61,
7947.
31 L. Valgimigli, J. T. Banks, J. Lusztyk and K. U. Ingold, J. Org.
Chem., 1999, 64, 3381.
32 K. Héberger, M. Walbiner and H. Fischer, Angew. Chem., Int. Ed.
Engl., 1992, 31, 635.
calculated EA values for C F CH᎐CH was checked by calcu-
᎐
6
5
2
lations on various C6H5X and C6F5X compounds for which
experimental EA values were also available45 (see Table 6). All
calculations were performed using the Gaussian 98 package.28
33 M. Walbiner and H. Fischer, J. Phys. Chem., 1993, 97, 4880.
34 J. Q. Wu and H. Fischer, Int. J. Chem. Kinet., 1995, 27, 167.
35 H. Fischer, in Substituent Effects in Radical Chemistry, ed. H. G.
Viehe, Z. Janousek and R. Merényi, D. Reidel Publ. Co., Dordrecht,
Germany, 1986, pp. 123–142.
36 K. Héberger and H. Fischer, Int. J. Chem. Kinet., 1993, 25, 913.
37 D. V. Avila, K. U. Ingold, J. Lusztyk, W. R. Dolbier, Jr., H.-Q. Pan
and M. Muir, J. Am. Chem. Soc., 1994, 116, 99; D. V. Avila, K. U.
Ingold, J. Lusztyk, W. R. Dolbier, Jr. and H.-Q. Pan, J. Org. Chem.,
1996, 61, 2027; D. V. Avila, K. U. Ingold, J. Lusztyk, W. R. Dolbier,
Jr. and H.-Q. Pan, Tetrahedron, 1996, 38, 1235.
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